Harvesting of blueberries is usually done from mid-August to early September, depending upon the location of the field and the weather conditions at that time. Typical growers may harvest fields ranging in size from 25 acres to 250 acres. Therefore, the harvesting of these fields must sometimes be done within a 2-3 weeks period.
When the cropland is relatively large, the harvesting task is too tedious to be done manually, or to be done by workers using manual implements. Therefore, there is a significant demand for self-propelled, efficient mechanical harvesters. A number of self-propelled apparatus for harvesting blueberries is available commercially. These machines, however, are not all very efficient, and in general, each type has inherent operational limitations.
One type of machine of the prior art is described in Canadian Patent no. 523,354 to L. C. Getsinger, April 1956. The machine has a drum, and a number of combs spaced apart at regular angular intervals and across the surface of the drum. The drum rotates against the direction of the travel of the machine such that the fingers of the combs intersect with berry plants and rake the fruits from these plants.
The combs are arranged to follow a cam groove so that the fingers withdraw within the surface of the drum at predetermined locations on the circumference of their course to facilitate the release of fruits onto a slide and into an exit conveyor.
Other similar self-propelled machines using articulated fingers mounted on a drum or along a chain moving against the direction of travel of the apparatus are described in the following documents:
Canadian Patent: 948,858 to G. L. Gray, June 1974; PA1 Canadian Patent: 961,275 to C. G. Burton, January 1975; PA1 U.S. Pat. No. 2,376,260 to A. M. Lobdell, May, 1945; PA1 U.S. Pat. No. 2,696,706 to L. C. Getsinger, December 1954; PA1 U.S. Pat. No. 2,783,605 to E. O. Heleen, March 1957; PA1 U.S. Pat. No. 2,795,099 to L. C. Getsinger, June 1957; PA1 U.S. Pat. No. 3,616,630 to G. L. Gray et al. November 1971; PA1 U.S. Pat. No. 3,648,447 to C. G. Burton, March 1972; PA1 U.S. Pat. No. 3,675,406 to Grant et al., July 1972; PA1 U.S. Pat. No. 4,141,204 to M. H. Kuryluk, February 1979. PA1 U.S. Pat. No. 5,369,944 to O. Robichaud, December 1994; PA1 U.S. Pat. No. 5,450,716 to L. Gidge, September 1995;
Another type of blueberry harvesting machinery available commercially is adapted to be mounted on a farm tractor, and is popular amongst Eastern Canada blueberry growers. The main characteristic of this machine is that the tines are mounted on a hollow drum and are adapted to discharge berries onto a conveyor mounted in the center of the drum. This machine is described in Canadian Patents no. 1,249,727 and 1,318,135, both to joint inventors D. R. Bragg and L. H. Weatherbee, and are dated February 1989 and May 1993 respectively. Another invention relating to this latter type of machine is disclosed in U.S. Pat. No. 5,375,403 to Collins et al., December 1994.
The apparatus of the prior art are known to have several limitations disfavouring their acceptance by commercial growers. For examples, the mechanisms to withdraw the tines inside the drum and to convey berries are mechanically complex, and therefore the purchase cost of one of these machines is sometimes considered prohibitive by small and medium size growers. The efficiency of these machines is often curtailed by the clogging of the fingers in each comb with leaves, twigs and squashed berries. The installation of the machines on a farm tractor is intensive work which is better done by the harvester's manufacturer himself. The installation of the machines on a farm tractor is more or less a permanent installation wherein the farm tractor is unavailable for doing other work during the blueberry harvest period. And finally, the gatherings of these machines are known to contain much leaves and debris. All these factors have contributed to the development of a market demand for better harvesting apparatus.